A number of malt beverages or beers will produce a relatively good foam immediately after pouring, but the foams so produced are not as persistent as is usually desired by the consumers of such products. In addition, consumers desire a beer possessing a foam that will "cling" to the insides of a glass or mug in an attractive "lacy" pattern. Lace and cling are difficult to achieve in the presence of slight contaminant levels of surfactants or detergents on the glassware, as occurs when beer mugs or glasses are handwashed and quickly rinsed prior to use. A further requirement is that the beer exhibit good clarity to the consumer, i.e., the absence of any noticeable "haze".
Propylene glycol alginate (PGA), heteropolysaccharide S-10 (see U.S. Pat. No. 3,966,976) and cellulose ether (see U.S. Pat. No. 3,669,00) are additives known to stabilize beer foam.
U.S. Pat. Nos. 4,720,389 and 4,729,900 teach the use of 1) xanthan gum and a galactomannan and 2) xanthan gum and a cold-water soluble protein, respectively, for malt beverage foam stability.
However, continuing research is being conducted in an effort to discover new polymers, additives, and polymer combinations which may be more economical and which can be utilized to impart improved foam stability, lace and clarity to fermented malt beverages while avoiding attendant "haze" levels.